Ace the 2026 Science Olympiad: Unleash Your Skills in the Integumentary System Challenge!

The stratum corneum is the outermost layer of the epidermis and plays a crucial role in the integumentary system. Its primary function is to provide a waterproof barrier and protect the underlying layers of skin from environmental damage. This layer is composed of dead skin cells that are tightly packed and filled with keratin, a protein that strengthens the surface and prevents water loss. This barrier is essential for maintaining hydration within the skin and for shielding the deeper layers from pathogens, chemicals, and physical abrasions.

Other functions mentioned in the options, such as promoting cell division and regeneration, are associated with deeper layers of the skin, such as the stratum basale. Similarly, vitamin D synthesis primarily occurs in the lower layers of the epidermis, and body temperature regulation is managed by sweat glands and blood vessels in the dermis rather than the stratum corneum. By understanding the specific protective function of the stratum corneum, it is clear why it is crucial for overall skin health and integrity.